The performance of some barley genotypes was evaluated under rain-fed conditions in Dara'a (Izra'a) during two successive growing seasons (2009-2010/ 2010-2011) in order to determine the most relevant physiological traits, which are genetically associated with drought tolerance and grain yield. The trial was laid out according to the factorial complete randomized block design, with three replicates. The leaf area index (LAI) was significantly lower in the wild relatives compared with the varieties and land races. Relative water content was significantly higher during the second growing season (87.19%) compared with the first one (71.57%). Solute leakage was significantly lower during the second growing season (69.50%) compared with the first growing season (76.49%). It was noticed that the genotypes which have achieved significantly higher grain yields, could also maintain significantly higher relative water content in the leaves, (Acsad176, Acsad1182 and Acsad60), and were superior in maintaining membrane integrity, and leaf area index, indicating the importance of such traits in improving drought tolerance and maintaining production capacity.